Classification automatique de nuages de points issus de LiDAR aéroporté par réseau à convolutions continues

Les données issues de LiDAR aéroporté permettent de modéliser de façon précise la topographie d’un territoire et sont utilisées dans différents contextes. Le processus de classification du nuage de points permet d’assigner une classe d’occupation du sol à chacun des points. La quantité et la répartition non homogène de ces points complexifient grandement l’automatisation de cette tâche. Pour certaines classes d’objets, les algorithmes traditionnels ne réussissent pas à classifier correctement les points avec un niveau de qualité satisfaisant. C’est le cas pour les classes "bâtiments", "plans d’eau" et "végétation". Ce faisant, cette étape nécessite une intervention manuelle importante afin de corriger la classification effectuée automatiquement, augmentant ainsi le coût de valorisation de ces données. Le succès des algorithmes d’apprentissage profond en vision par ordinateur a mené à une révolution dans différents domaines, notamment en traitement d’images satellitaires. Ces succès ont inspiré diverses recherches sur la classification de nuages de points. La plupart de ces recherches portent sur le traitement de nuages de points issus de LiDAR mobile terrestre, mais elles peuvent très bien être adaptées pour le traitement de données LiDAR aéroporté. Cette recherche vise à utiliser une méthode d’apprentissage profond pour permettre une automatisation du processus de classification de nuages de points aéroportés, en évaluant une méthode sur deux jeux de données de contextes variés (urbain et rural), puis en modifiant la méthode de sélection des sous-ensembles de points pour qu’elle soit adaptée à la densité locale. La méthode originale a été testée sur deux jeux de données couvrant près de 16 000 km2, près de Montréal (QC) et de St-Jean (NB) et l’amélioration a été évaluée sur le jeu de données de référence DALES. La méthodologie utilisée est basée sur une adaptation de l’opération de convolution de Boulch (2020) appelée ConvPoint. Cette opération de convolution continue a été utilisée dans une architecture de type encodeur-décodeur qui permet de classifier les points directement, sans avoir recours à une étape de sursegmentation. En expérimentant avec différentes configurations, nous avons obtenu d'excellents résultats d'Intersection-sur-Union (IoU) pour les classes "Végétation moyenne-haute" (93 %) et "Bâtiment" (86 %) sur les ensembles de données de Montréal et Saint-Jean. La taille de bloc adaptative a conduit à certains gains de performances sur le jeu de données de référence DALES ainsi qu'à une sensibilité réduite aux hyperparamètres de la ConvPoint

Contra todas as probabilidades: Previsão das eleições presidenciais brasileiras em tempos de ruptura política

When the number of observed elections is low, subnational data can be used to perform electoral forecasts. Turgeon and Rennó (2012) applied this solution and proposed three forecasting models to analyze Brazilian presidential elections (1994-2006). The models, adapted from forecasting models of American and French presidential elections, considers economic and political factors. We extend their analysis to the recent presidential elections in Brazil (2010, 2014 and 2018) and find that the addition of the three recent elections does not improve the accuracy of our forecast models although it strengthens the relationship between the explanatory variables and vote for the incumbent. We also find that models based on the popularity of the incumbent outperform those based on trial-heat polls and that electoral forecast models can survive earthquake elections like the 2018 election that led to the unexpected rise of "outsider" and extremist candidate Jair Bolsonaro.Cuando el número de elecciones observadas es bajo, se puede usar datos subnacionales para hacer predicciones electorales. Turgeon y Rennó (2012) aplicaron esta solución y propusieron tres modelos de predicción para analizar las elecciones presidenciales brasileñas entre 1994 y 2006. Los modelos, adaptados de los modelos de predicción de elecciones presidenciales de Estados Unidos y Francia, consideran factores económicos y políticos. Extendemos este análisis a las recientes elecciones presidenciales en Brasil (2010, 2014 y 2018) y demostramos que la adicción de las tres elecciones más recientes no mejora la precisión de los modelos predictivos, aunque fortalece la relación entre las variables explicativas y el voto por el titular. También concluimos que los modelos basados en la popularidad del titular superan a los basados en encuestas electorales y que los modelos de predicción electoral pueden sobrevivir a elecciones ruidosas como la de 2018, que condujo al ascenso inesperado de un candidato de la extrema derecha, Jair Bolsonaro.Quando o número de eleições observadas é baixo, pode-se usar dados subnacionais para realizar previsões eleitorais. Turgeon e Rennó (2012) aplicaram essa solução e propuseram três modelos de previsão para analisar eleições presidenciais brasileiras ocorridas entre 1994 e 2006. Os modelos, adaptados de modelos de previsão de eleições presidenciais americanas e francesas, consideram fatores econômicos e políticos. Estendemos esta análise para as recentes eleições presidenciais no Brasil (2010, 2014 e 2018) e demonstramos que a adição das três eleições mais recentes não melhora a precisão dos modelos preditivos, embora fortaleça a relação entre as variáveis explicativas e o voto no incumbente. Também concluímos que os modelos baseados na popularidade do incumbente superam aqueles baseados em pesquisas eleitorais e que os modelos de previsão eleitoral podem sobreviver a eleições com muito ruído, como a de 2018, que levou à ascensão inesperada de um candidato de extrema-direita, Jair Bolsonaro

Desproporcionalidade da representação na câmara dos deputados : análise dos efeitos sobre o sistema partidário no Brasil

Este trabalho analisa de forma sistemática e abrangente os efeitos da desproporcionalidade da representação dos estados (malapportionment) sobre o viés partidário – isto é, a distribuição desigual de cadeiras legislativas entre partidos, por votos recebidos. Especificamente, examinam-se esses efeitos no âmbito da Câmara dos Deputados, de 1994 a 2010. Primeiro, utiliza-se o modelo econométrico bilogit multinominal proposto por King (1990), para analisar a responsividade eleitoral do sistema brasileiro, que se revelou elevada. Em seguida, adaptando-se a estratégia analítica de Grofman, Koetzle e Brunell (1997) ao sistema multipartidário com distritos plurinominais, e após se extrair os efeitos das coligações eleitorais, encontram-se resultados que sugerem fortes efeitos da desproporcionalidade da representação dos estados sobre o viés partidário no Brasil. Esses efeitos, entretanto, variam consideravelmente entre partidos e eleições. _______________________________________________________________________________________________ ABSTRACTThis paper offers a systematic and comprehensive analysis of the effects of malapportionment on partisan bias, that is, the uneven distribution of legislative seats among parties for votes received. Specifically, it examines such effect in the Brazilian Lower Chamber from 1994 to 2010. First, we use King’s (1990) multinomial bilogit model to analyze the responsiveness of the Brazilian electoral system, which revealed to be quite high. Second, adapting the analytical strategy of Grofman, Koetzle e Brunell (1997) to multi-party system and multi-member districts, and after extracting the effects of electoral coalitions, we found results that suggest strong malapportionment effects on partisan bias in Brazil. These effects, however, vary considerably by parties and elections

E se soubéssemos mais? Simulando os votos e as opiniões dos eleitores mais informados no Brasil

RESUMO Introdução: Décadas de pesquisas sobre a opinião pública demonstraram que a maioria das pessoas é altamente desinformada a respeito da política. Entretanto, as consequências dessa desinformação sobre o comportamento eleitoral e sobre as atitudes dos cidadãos ainda parecem pouco claras, especialmente quando se trata de jovens democracias. Métodos: Neste artigo, utilizamos simulações estatísticas de um eleitorado “completamente informado” a partir de dados do Estudo Eleitoral Brasileiro (ESEB) para responder às seguintes perguntas: (1) Como os brasileiros votariam caso fossem mais informados? (2) Como seriam as opiniões políticas dos brasileiros caso fossem mais informados? Aqui, "informação" se refere a conhecimento sobre a política e o governo de maneira geral. Resultados: Os resultados sugerem que os votos e as opiniões políticas dos brasileiros seriam diferentes caso eles fossem mais informados. A falta de informação parece direcionar sistematicamente as preferências coletivas, sugerindo que tais erros não são aleatórios, mas sim produto de assimetrias de informação entre os cidadãos. Discussão: Essas assimetrias podem ser especialmente problemáticas quando se trata de quais opiniões são levadas em consideração pelos representantes dos eleitores, ao tomarem decisões importantes. Os efeitos da desinformação política têm sido vistos sob diferentes olhares pela Ciência Política. Embora alguns teóricos argumentem que a falta de informação não tem efeitos significativos sobre a democracia, outros creem que ela pode trazer consequências notáveis para as escolhas coletivas e para as atitudes políticas dos cidadãos. Nossos resultados nos colocam ao lado do segundo grupo de pesquisadores

Mecanismos de difusão de políticas sociais no Brasil : uma análise do programa saúde da família

Nas últimas décadas, os estudos de difusão de políticas têm recebido grande atenção, especialmente nos EUA e na Europa. Estas pesquisas identificaram o papel dos fatores internos (características endógenas) e externos (características exógenas) para explicar fenômenos de difusão de inovações políticas. Os eventos de difusão, no entanto, também estão proximamente relacionados à questão temporal haja vista que muitas vezes as adoções ocorrem devido a existência simultânea de fatores em grandes intervalos de tempo. Neste trabalho, propomos explorar a difusão de políticas sociais de saúde no Brasil. O artigo inova ao analisar conjuntamente o papel dos fatores internos e externos usando uma unidade de análise não convencional para o campo de estudos, ou seja, governos locais. Para a análise é importante notar que a Constituição de 1988 reconhece os municípios como jurisdições autônomas, dando-lhes a prerrogativa constitucional para adotar ou não uma política social do governo federal. Que fatores determinam a difusão do Programa Saúde da Família? Para responder essa questão aplicamos a metodologia Event History Analysis utilizando dados para cerca de 5.560 municípios no período 1997-2010. Os resultados demonstram que competição política e ideologia influenciam a difusão horizontal e vertical entre os municípios. Surpreendentemente, eleições municipais também influenciam a emulação da política. _______________________________________________________________________________ ABSTRACTIn recent decades, the study of policy diffusion has received a great deal of attention, especially in the U.S. and in Europe. These studies have identified the role of internal (i.e., characteristics proper to the unit of analysis) and external (i.e., characteristics outside the unit of analysis) factors in explaining innovation of policy diffusion. Events of diffusion is also closely related to a time issue because the adoption often requires the simultaneous occurrence of factors in large intervals of time to take place. In this paper, we propose to explore the diffusion of social health policies in Brazil. This paper innovates by examining at the same time the role of internal and external factors using a nonconventional unit analysis to the field of study, namely local governments. To the analyses it is worth noting that the 1988 Brazilian Constitution recognizes municipalities as autonomous jurisdictions, giving them broad latitude over policymaking. What factors determine the spread of Programa Saúde da Família? To answer these question we adopt an event history analysis using data from over 5,560 municipalities over a period 1997-2010. The findings show that political competition and ideology drive the horizontal and vertical diffusion among municipalities. Surprisingly, municipal elections also drive policy emulation

Effect of Hydrocortisone on Mortality and Organ Support in Patients With Severe COVID-19: The REMAP-CAP COVID-19 Corticosteroid Domain Randomized Clinical Trial.

Importance: Evidence regarding corticosteroid use for severe coronavirus disease 2019 (COVID-19) is limited. Objective: To determine whether hydrocortisone improves outcome for patients with severe COVID-19. Design, Setting, and Participants: An ongoing adaptive platform trial testing multiple interventions within multiple therapeutic domains, for example, antiviral agents, corticosteroids, or immunoglobulin. Between March 9 and June 17, 2020, 614 adult patients with suspected or confirmed COVID-19 were enrolled and randomized within at least 1 domain following admission to an intensive care unit (ICU) for respiratory or cardiovascular organ support at 121 sites in 8 countries. Of these, 403 were randomized to open-label interventions within the corticosteroid domain. The domain was halted after results from another trial were released. Follow-up ended August 12, 2020. Interventions: The corticosteroid domain randomized participants to a fixed 7-day course of intravenous hydrocortisone (50 mg or 100 mg every 6 hours) (n = 143), a shock-dependent course (50 mg every 6 hours when shock was clinically evident) (n = 152), or no hydrocortisone (n = 108). Main Outcomes and Measures: The primary end point was organ support-free days (days alive and free of ICU-based respiratory or cardiovascular support) within 21 days, where patients who died were assigned -1 day. The primary analysis was a bayesian cumulative logistic model that included all patients enrolled with severe COVID-19, adjusting for age, sex, site, region, time, assignment to interventions within other domains, and domain and intervention eligibility. Superiority was defined as the posterior probability of an odds ratio greater than 1 (threshold for trial conclusion of superiority >99%). Results: After excluding 19 participants who withdrew consent, there were 384 patients (mean age, 60 years; 29% female) randomized to the fixed-dose (n = 137), shock-dependent (n = 146), and no (n = 101) hydrocortisone groups; 379 (99%) completed the study and were included in the analysis. The mean age for the 3 groups ranged between 59.5 and 60.4 years; most patients were male (range, 70.6%-71.5%); mean body mass index ranged between 29.7 and 30.9; and patients receiving mechanical ventilation ranged between 50.0% and 63.5%. For the fixed-dose, shock-dependent, and no hydrocortisone groups, respectively, the median organ support-free days were 0 (IQR, -1 to 15), 0 (IQR, -1 to 13), and 0 (-1 to 11) days (composed of 30%, 26%, and 33% mortality rates and 11.5, 9.5, and 6 median organ support-free days among survivors). The median adjusted odds ratio and bayesian probability of superiority were 1.43 (95% credible interval, 0.91-2.27) and 93% for fixed-dose hydrocortisone, respectively, and were 1.22 (95% credible interval, 0.76-1.94) and 80% for shock-dependent hydrocortisone compared with no hydrocortisone. Serious adverse events were reported in 4 (3%), 5 (3%), and 1 (1%) patients in the fixed-dose, shock-dependent, and no hydrocortisone groups, respectively. Conclusions and Relevance: Among patients with severe COVID-19, treatment with a 7-day fixed-dose course of hydrocortisone or shock-dependent dosing of hydrocortisone, compared with no hydrocortisone, resulted in 93% and 80% probabilities of superiority with regard to the odds of improvement in organ support-free days within 21 days. However, the trial was stopped early and no treatment strategy met prespecified criteria for statistical superiority, precluding definitive conclusions. Trial Registration: ClinicalTrials.gov Identifier: NCT02735707

Surviving Sepsis Campaign: international guidelines for management of severe sepsis and septic shock, 2012

OBJECTIVE: To provide an update to the "Surviving Sepsis Campaign Guidelines for Management of Severe Sepsis and Septic Shock," last published in 2008. DESIGN: A consensus committee of 68 international experts representing 30 international organizations was convened. Nominal groups were assembled at key international meetings (for those committee members attending the conference). A formal conflict of interest policy was developed at the onset of the process and enforced throughout. The entire guidelines process was conducted independent of any industry funding. A stand-alone meeting was held for all subgroup heads, co- and vice-chairs, and selected individuals. Teleconferences and electronic-based discussion among subgroups and among the entire committee served as an integral part of the development. METHODS: The authors were advised to follow the principles of the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system to guide assessment of quality of evidence from high (A) to very low (D) and to determine the strength of recommendations as strong (1) or weak (2). The potential drawbacks of making strong recommendations in the presence of low-quality evidence were emphasized. Recommendations were classified into three groups: (1) those directly targeting severe sepsis; (2) those targeting general care of the critically ill patient and considered high priority in severe sepsis; and (3) pediatric considerations. RESULTS: Key recommendations and suggestions, listed by category, include: early quantitative resuscitation of the septic patient during the first 6 h after recognition (1C); blood cultures before antibiotic therapy (1C); imaging studies performed promptly to confirm a potential source of infection (UG); administration of broad-spectrum antimicrobials therapy within 1 h of the recognition of septic shock (1B) and severe sepsis without septic shock (1C) as the goal of therapy; reassessment of antimicrobial therapy daily for de-escalation, when appropriate (1B); infection source control with attention to the balance of risks and benefits of the chosen method within 12 h of diagnosis (1C); initial fluid resuscitation with crystalloid (1B) and consideration of the addition of albumin in patients who continue to require substantial amounts of crystalloid to maintain adequate mean arterial pressure (2C) and the avoidance of hetastarch formulations (1B); initial fluid challenge in patients with sepsis-induced tissue hypoperfusion and suspicion of hypovolemia to achieve a minimum of 30 mL/kg of crystalloids (more rapid administration and greater amounts of fluid may be needed in some patients (1C); fluid challenge technique continued as long as hemodynamic improvement is based on either dynamic or static variables (UG); norepinephrine as the first-choice vasopressor to maintain mean arterial pressure ≥65 mmHg (1B); epinephrine when an additional agent is needed to maintain adequate blood pressure (2B); vasopressin (0.03 U/min) can be added to norepinephrine to either raise mean arterial pressure to target or to decrease norepinephrine dose but should not be used as the initial vasopressor (UG); dopamine is not recommended except in highly selected circumstances (2C); dobutamine infusion administered or added to vasopressor in the presence of (a) myocardial dysfunction as suggested by elevated cardiac filling pressures and low cardiac output, or (b) ongoing signs of hypoperfusion despite achieving adequate intravascular volume and adequate mean arterial pressure (1C); avoiding use of intravenous hydrocortisone in adult septic shock patients if adequate fluid resuscitation and vasopressor therapy are able to restore hemodynamic stability (2C); hemoglobin target of 7-9 g/dL in the absence of tissue hypoperfusion, ischemic coronary artery disease, or acute hemorrhage (1B); low tidal volume (1A) and limitation of inspiratory plateau pressure (1B) for acute respiratory distress syndrome (ARDS); application of at least a minimal amount of positive end-expiratory pressure (PEEP) in ARDS (1B); higher rather than lower level of PEEP for patients with sepsis-induced moderate or severe ARDS (2C); recruitment maneuvers in sepsis patients with severe refractory hypoxemia due to ARDS (2C); prone positioning in sepsis-induced ARDS patients with a PaO (2)/FiO (2) ratio of ≤100 mm Hg in facilities that have experience with such practices (2C); head-of-bed elevation in mechanically ventilated patients unless contraindicated (1B); a conservative fluid strategy for patients with established ARDS who do not have evidence of tissue hypoperfusion (1C); protocols for weaning and sedation (1A); minimizing use of either intermittent bolus sedation or continuous infusion sedation targeting specific titration endpoints (1B); avoidance of neuromuscular blockers if possible in the septic patient without ARDS (1C); a short course of neuromuscular blocker (no longer than 48 h) for patients with early ARDS and a PaO (2)/FI O (2) 180 mg/dL, targeting an upper blood glucose ≤180 mg/dL (1A); equivalency of continuous veno-venous hemofiltration or intermittent hemodialysis (2B); prophylaxis for deep vein thrombosis (1B); use of stress ulcer prophylaxis to prevent upper gastrointestinal bleeding in patients with bleeding risk factors (1B); oral or enteral (if necessary) feedings, as tolerated, rather than either complete fasting or provision of only intravenous glucose within the first 48 h after a diagnosis of severe sepsis/septic shock (2C); and addressing goals of care, including treatment plans and end-of-life planning (as appropriate) (1B), as early as feasible, but within 72 h of intensive care unit admission (2C). Recommendations specific to pediatric severe sepsis include: therapy with face mask oxygen, high flow nasal cannula oxygen, or nasopharyngeal continuous PEEP in the presence of respiratory distress and hypoxemia (2C), use of physical examination therapeutic endpoints such as capillary refill (2C); for septic shock associated with hypovolemia, the use of crystalloids or albumin to deliver a bolus of 20 mL/kg of crystalloids (or albumin equivalent) over 5-10 min (2C); more common use of inotropes and vasodilators for low cardiac output septic shock associated with elevated systemic vascular resistance (2C); and use of hydrocortisone only in children with suspected or proven "absolute"' adrenal insufficiency (2C). CONCLUSIONS: Strong agreement existed among a large cohort of international experts regarding many level 1 recommendations for the best care of patients with severe sepsis. Although a significant number of aspects of care have relatively weak support, evidence-based recommendations regarding the acute management of sepsis and septic shock are the foundation of improved outcomes for this important group of critically ill patients

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

'Just thinking': political thought and political attitudes

textThis dissertation looks at political attitudes. The determinants of political attitudes are numerous, but recent work paid particular attention to information. Information undoubtedly matters, but so does the thought given to information already held. Using data from two originally designed survey-experiments conducted in Brazil and in the U.S., I examine the ways in which thought, alone or in combination with information, affect attitudes from three different angles: the effects of thought on the development, authenticity, and extremity and polarization of political attitudes. Attitude development matters because public opinion polls matter. They inform representatives about what people want, fuel public debate, and affect policymaking. Examining the effects of thought on attitude development is thus of great interest because the value of polls depends heavily on how many voices are heard and how that affects the aggregate distribution of attitudes. Attitude authenticity refers to holding attitudes that are reflective of underlying interests. It also matters because electoral democracy requires a competent citizenry, and citizen competence is partly defined by the citizenry’s ability to express political attitudes and preferences that reflect their interests. This ability is, of course, particularly important during elections and referenda, but also when citizens are asked about their attitudes and preferences in surveys because the latter affect policymaking. Attitude extremity refers to the degree to which one holds an attitude that is further away from the middle. Polarization, on the other hand, is the possible aggregate consequence of attitude extremity. Studying the effects of thought on attitude extremity and polarization is important because it may suggest ways in which public opinion can change when given issues receive increased attention by the media and the political elites. Finally, it is worth noting that the results presented also provide useful insights into survey, and specifically questionnaire design.Governmen